One potential source of jitter within an electronic circuit arises from the simultaneous switching of synchronous circuit elements. When the output of a synchronous circuit element transitions from one state to another on a clock edge, the circuit element generates a current pulse that occurs on the clock edge. Each synchronous circuit element that transitions on a same clock edge contributes to the current pulse. The more synchronous circuit elements switching at the same time, the larger the resulting current pulse.
Because of the large number of synchronous circuit elements within a modern IC design, the transitioning of synchronous circuit elements on any given clock edge within a selected clock domain becomes randomized. This randomization means that for each clock edge within the selected clock domain, approximately a same number of synchronous elements will transition. As a result, the electronic circuit generates a current pulse of substantially the same magnitude on each clock transition edge of the clock domain.
Each current pulse, however, causes a fluctuation in the internal power grid of the electronic circuit. More particularly, the supply voltage provided to various circuit elements within the electronic circuit fluctuates by a small amount that is proportional to the size of the current pulses that are generated. This fluctuation in the power supply voltage induces unwanted jitter that may reduce performance of the electronic circuit.